African Americans (AA) are at greater risk of developing End Stage Renal Disease (ESRD) than others. Most believe this is due to a greater prevalence of hypertension among AAs and that hypertension is more harmful to kidneys in AAs. The evidence that the incidence of hypertension is higher in AAs is strong, but how it causes ESRD and is more harmful to kidneys is less well understood. We, and others, have noted that first degree relatives of AA, who have ESRD due to hypertension, are at greater risk of also having ESRD - although not necessarily form hypertension. We will examine first degree relatives of patients (study patients) with ESRD and compare them to patients AAs who do not have a first degree relative with ESRD (controls). The hypothesis is that the study patients will have detectable progressive loss of renal function that predates obvious clinical hypertension (BP >140/90) and those with progressive loss of renal function will be "salt sensitive", and have low plasma renin activity compared to study patients without progressive renal function loss and the control group. This study will advance our knowledge of how kidney disease develops in AAs, and if the hypothesis is correct, provide an early screening process to detect patients who are at high risk of developing renal failure.